CF HttpWebRequest does not allow writing to the request stream by default

While trying to send data via a request stream, I ran into this error in the compact framework:
ex = {"Either ContentLength must be set to a non-negative number, or SendChunked set to true in order to perform the write operation when AllowWriteStreamBuffering is disabled."}

This was a bit confusing since I didn't get this error when running from a windows client.  I finally figured out that I have to allow writing to the stream:

private void SendData(WebRequest request, object dto)
{
   // I had to add this for the CF framework. It isn't true by default.
   if (request is HttpWebRequest)
      ((HttpWebRequest) request).AllowWriteStreamBuffering = true;

   using (Stream requestStream = request.GetRequestStream())
   {
         if (IsJsonRequest(request))
            SendDataAsJson(requestStream, dto);
        else SendDataAsXml(requestStream, dto);
   }
}